Chemical properties mean properties that involve chemical changes. Here we discuss chemical resistance and hygroscopicity
①Chemical resistance
In general, the chemical resistance of plastics is affected by the effects of organic chemicals (solvents, oils) and the effects of acids and alkalis.
The table shows the resistance of plastics to various chemicals.
In addition, even if the chemicals shown in the table are judged to be practicable, cracks may occur if they come into contact with the molded product under strain (internal strain during molding, fastening strain, or strain due to other external forces). . This is called environmental stress cracking.
Cracks may occur when contacting with grease, mold release agent, mold rust inhibitor, paint, wiping thinner, hot stamping, and soft PVC. It is better to contact a material manufacturer with dedicated equipment, as the danger cannot be predicted unless the test is performed under strain.
②Hygroscopicity
If the plastic material is immersed in water for a long time or left in a high humidity atmosphere, it absorbs water and gains weight. This property is called hygroscopicity or water absorption
In general, the degree of water absorption affects the electrical properties, mechanical properties and dimensions of the material.
▶Light resistance of plastics
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